Refrigerating devices are known to have configurations such that, in order to prevent breakages and lower performance of a compressor which configures a refrigerant circuit due to overheating, a temperature of a discharge pipe of the compressor is monitored and a protection control is performed on the compressor when this temperature is larger than a determination temperature.
To protect the compressor, it is more preferable to monitor the internal temperature of the compressor, which is higher than the temperature of the discharge pipe, in more detail, to monitor the temperature of refrigerant immediately after being discharged from a compression chamber (the temperature of a discharge port) or the temperature of a motor, than to monitor the temperature of the discharge pipe of the compressor. However, it is difficult to install a temperature detector in the compressor interior because this leads to an increase in manufacturing cost; therefore, a determination temperature is decided with the presupposition that there will be a fixed temperature difference between the internal temperature of the compressor and the temperature of the discharge pipe, and protection control is performed using the temperature of the discharge pipe of the compressor.
However, when an inverter compressor is used, the circulating amount of refrigerant changes, and the temperature difference between the internal temperature of the compressor and the temperature of the discharge pipe could therefore change as well. With regard to this, Japanese Laid-open Patent Application No. 2002-107016 discloses a configuration in which the determination temperature is varied according to the driving frequency of the inverter compressor (the circulating amount of refrigerant).